fix(server): accept SERVER_PORT alias and fail fast on PORT/SERVER_PORT mismatch

[Ayush7614]

Problem

The server only read PORT (server/src/index.ts:146):

ts const port = Number.parseInt(process.env.PORT ?? "3001", 10);

while scripts/start.sh and app/vite.config.ts honour SERVER_PORT/APP_PORT, and docs/configuration.md + .env.example document SERVER_PORT as the setting. An operator who followed the docs and set SERVER_PORT=4000 (or edited only PORT) ended up with:

• server on 3001
• Vite proxy + start.sh health-check on 4000
• 200 from whatever else was on 3001 accepted as proof, then HTML parsed as JSON several stages later

Dockerfile/compose masked it because they set PORT directly.

Fix

• server/src/index.ts:145-155: read PORT ?? SERVER_PORT ?? "3001", preferring PORT but falling back to SERVER_PORT. If both are set and disagree, throw at boot where somebody is looking instead of failing late as a JSON parse error.
• .env.example:10-20: comment updated to describe the alias behaviour and that a single edit now suffices (both equal remains valid).

Behaviour verified:

PORT=4000 -> 4000
SERVER_PORT=4000 -> 4000
PORT=4000 SERVER_PORT=4000 -> 4000
PORT=4000 SERVER_PORT=4001 -> throw "PORT (4000) and SERVER_PORT (4001) disagree"

Verification

bun run lint — pass (0 warnings)
bun run format:check — pass
Manual port-logic checks above — pass
No schema, migration, or dependency changes.

[davidmckayv]

Correct, and the hard failure is the right one: the trap the .env.example comment already described at length was a silent misconfiguration, and this makes it loud. Checked the deploy paths, nothing sets PORT and SERVER_PORT to different values (the PORT: "4300" in docker-compose.yml is the supervisor, a different process). CI green.